Control and indicator for supersonic vehicles



June 27, 1950 F. A. CLEVELANDJE 2,512,790

CONTROL AND INDICATQR FOR SUPERSONIC VEHICLES Filed Jan. 9, 194a 4 Shets-Sheet 1 INVENTOR. FRANK A. CLEVELANDJI Agent June 27, 1950 F. A. CLEVELANDJI 2,512,790

CONTROL AND INDICATOR FOR SUPERSONIC VEHICLES Filed Jan. 9, L948 4 Sheets-Sheet 2 'INVENTOR. FRANK A. CLEVELANDII Agent 558mm Swim June 27, 1950 F. A. CLEVELANDJI 2,512,790

CONTROL AND INDICATOR FOR SUPERSONIC VEHICLES Filed Jan. 9, 1948 4 Sheets-Sheet 3 INVENTOR.

FRANK A. CLEVELANDII Argent June 27, 1950 F. A. cLEvELA'NDJI;

cou'mor. AND INDICATOR FOR SUPER-SONIC VEHICLES Filed Jan. 9, 1948 4 Sheets-Sheet 4 INVENTOR. FRANK A. CLEVELANDII nofii no 305 a mp6:

HzoEmon. wmomu Agent Patented June 27, 1950 CONTROL AND INDICATOR FOR SUPER/SONIC VEHICLES Frank A. Cleveland, II, Pasadena, Calif., assignor to Lockheed Aircraft Corporation, Burbank,

Calif.

Application January 9, 1948, Serial No. 1,363

22 Claims. 1

This invention relates toairborne craft such as airplanes and guided missiles designed for supersonic flight, and relates more particularly to controls and velocity indicators for such aircraft.

When an airborne craft operates at a speed in excess of the speed of sound, that is in the supersonic region, the conventional air speed indicators are no longer capable of measuring the air speed due to compressibility effects and shock phenomena. At supersonic velocities the total head tube of-a conventional indicator indicates a total pressure value considerably below the true value and the static pressure oriflces'do not provide a true ambient static pressure reading. Even assuming that the head tube and the static pressure tubes are capableof correctly reading the true pressures, the difference in these pressures during supersonic flight 'is nolonger a definitive function or" air speed either indicated or true and this error, which begins below'th'e speed of sound, increases in magnitude as the velocity of the craft increases. A calibrated chart might conceivably be employed to correct the error but such a chart would be useful only if 1e ambient static pressure could be accurately determined which is extremely diflicult at supersonic speeds.

In the operation of an airplane, and more particularly in the case of aguided missile, there are certain operations and functions whichmay be controlled by or made dependent .uponthe translational velocity of the craft. For example,'in the case of a guided missile powered by a ram jet engine or a turbo powerplant, the velocity and mass of the reactive propulsive jet of gases and air may be regulated to maintain a desired or predetermined speed of flight. Such regulation may well be accomplished by varying the fuel supplied to the engine in accordance with the actual speed of flight. Another example is an air brake system that is responsive to the velocity of the craft. Without a device that is capable of accurately determining the translational velocity in the sonic and supersonic regions, it. is,

of course, impossible to properly control such functions either automatically or through the medium or intervention of a human pilot.

The pilot and aerodynamast interested in the design, operation and characteristics of craft intended for supersonic flight are concerned-primarily with the Mach number of" the craft, that is the ratio of local velocity to'the local velocity of sound, and the so-called true or indicated air speed is of little or no significance. Accordingly,

2 it is a primary concern'to accurately determine the Mach number of such a craft during flight.

It is an object of the present invention to provide a practical, effective, and dependable device or means for accurately determining and/0r indicating the Mach number of craft traveling at supersonic velocities. The device of the present invention is useful as a Mach'meter which provides a visible reading or indication of the speed of the craft and may, additionally or alternatively, serve as a control for initiating or governing actuation of other instrumentalities of the craft .such as the powerplant, air brakes, etc.

Another object 'of the invention is to provide a device of the 'character referred to that determines theMach number ofthe missile or craft by sensing the position of a supersonic shock wave Whose position is solely and exclusively a true indication or direct function of the Mach number of flight. When a total pressure tube, such as employed in a conventional air speed indicator, is placed in a supersonic airstream, a-shock wave forms directly in front of the tube and the total pressure in the region behind the wave occupied bythe tube is much lower than the true free stream total pressure. This differential between the pressure received by the tube and the total pressure of the true free stream increases as the Mach number increases. It is this phenomena that exists when a conventional air speed indicator is used at supersonic velocities. In the present invention on the other hand, a substantially wedge shaped object is placed in the air stream to generate a shock waveandthe angle of this Wave with respect to the free stream is always a function of the half angleof the wedge and the free stream Mach number or speed. Since the half angle of the wedge'is known and constant, measurementof the shockwave angle determines the Mach number of the free air stream. Accordingly-the device of theinvention, by sensing the position of the shock waveangle, accurately senses and measuresthe Mach number of flight of the aircraft.

Another object of the invention is to provide a device of the character .mentioned embodying means for automatically compensating for changesin the angle of, attack ofuthe airplaneor vehicle. -When the angle between the free air stream and the above referred to wedge changes, that iswhen there is a changeinthe angle of at tack, an-error'is introduced into the indications unless provision is made to correct or compensate 'for'this change. The present invention embodies means for automatically maintaining the wedge at a substantially zero angle of attack even during changes in the angle of attack of the vehicle or craft, thus assuring accurate functioning of the above mentioned shock wave sensing mechanism. Static pressure taps are provided at the opposite sides of the wedge to sense the angle of attack of the wedge and the pressures thus obtained are employed to control a mechanism for moving the wedge in a manner to preserve it in the zero angle of attack position.

A further object of the invention is to provide a fuel control for the propulsive engine of an airborne vehicle that senses and responds to the Mach number of the vehicle to regulate the fuel supplied to the engine. The fuel control system may be manually or mechanically adjusted to a selected Mach number setting and will thereafter sense or read the Mach number of the craft and regulate the delivery of fuel to the engine accordingly to preserve a Mach number corresponding to the setting thus selected.

A still further object of the invention is to provide an air brake regulating system that automatically responds to the Mach number of flight of the craft. The system utilizes the above men tioned shock wave sensing mechanism and automatically governs the position or extent of projection of the air brake elements in accordance with the Mach number indications thus obtained. The system may be manually or mechanically adjusted to produce the desired action of the brake elements at the selected Mach number settings.

Other objectives and advantages of the invention will become apparent from the following detailed description of a typical preferred form of the invention throughout which description reference is made to the accompanying drawings wherein:

Figure 1 is a more or less diagrammatic fragmentary perspective view of an airplane embodying the mechanism of the present invention with the overlying portions of the airplane broken away to illustrate the elements of the mechanism;

Figure 2 is an enlarged vertical sectional view of the shock wave sensing elements and related mechanisms with certain parts appearing in side elevation;

Figure 3 is a perspective view of the shock wave sensing mechanism with the rear portion of the r same broken away;

Figures 4 and 4A are enlarged side elevations of the signal receivers and the associated adjusting mechanisms;

Figure 5 is an enlarged side elevation of the actuator for the fuel control system;

Figures 6 and '7 are elevational views of the rheostat and adjusting dial respectively taken as indicated by lines 6-6 and 'l'! on Figure l;

Figure 8 is a fragmentary side elevation of the air brake actuating device;

Figure 9 is a perspective view of the Mach meter;

Figure 10 is a wiring diagram of the circuits embodied in the apparatus; and

Figure 11 is an enlarged sectional view of one of the switch adjusting means.

In the drawings I have illustrated the invention embodied in or applied to an aircraft propelled by an internal combustion turbo powerplant of the reactive jet type. The apparatus of the invention, as illustrated, is operable to provide a visible indication of the supersonic velocity or Mach number of the craft, to control or regulate the delivery of fuel to the powerplant P and/or 4 to regulate one or more air brakes B. It will become apparent from the following detailed description that the invention is capable of other adaptations and applications and, therefore, is not to be considered as confined to the particular embodiment and application herein disclosed.

The portion of the aircraft illustrated includes a body or fuselage I!) provided with wings l I and housing the powerplant P. The aircraft may be considered as carrying a human pilot and the fuselage i8 is provided with a pilots cockpit I2. The owerplant P has air intake ducts !3 for receiving ram air and an exhaust nozzle i i for discharging the combustion gases and compressed air in the form of a reactive propulsion jet. The engine P also has a plurality of combustion tubes or chambers 15 supplied with a suitable fluid fuel by a ring manifold l6 which, in turn, is supplied with the fuel by a line or pipe [1. The pipe I! leads to a suitable source l8 of fuel, diagrammatically illustrated in Figure l. The details and construction of internal combustion turbo powerplants of the type illustrated are now well known to those skilled in the art and have been omitted from the present disclosure as unnecessary to a full understanding of the invention.

Figures 1 and 8 illustrate in a more or less diagrammatic manner, an air brake B pivoted in a wing H at E9. The brake B has an elongate out-turned part 2c adapted to project through a slot 2! in the skin of the wing ll so as to extend into the slip-stream. The braking efiect obtained. depends upon the amount of projection of the active part 26. It is to be understood that the brake B may be installed at any selected location on the aircraft and there may be two or more such brakes B, for example there may be a brake on each wing H.

The apparatus of the invention may be said to include an element 25 positioned in the free air stream and operable to create a shock wave W during supersonic flight of the craft, means 25 for sensing the position or angle of the wave W, means 27 for adjusting the position of the means 26 to compensate for changes in the angle of attack, an indicator 28 responsive to the wave sensingv means 25 to indicate the Mach number of the craft, means 29 responsive to the wave sensing means 26 for regulating the fuel supply line ll of the powerplant P, and a means 30 for actuating or controlling the brake B also responsive to the wave sensing means 26.

The element 25 for producing the shock wave is arranged or positioned on the vehicle to be in the free air stream. In accordance with the invention, it is contemplated that the element 25 may be placed in any appropriate or selected location on the craft, for example it may be arranged on the forward end of the fuselage H3 or at the leading edge of the wing H or a vertical stabilizer. In the diagrammatic illustration of Figure l, the element 25 is arranged ahead of the leading edge of a wing H. The element 25 is in the nature of a wedge being a somewhat elongated part provided with upper and lower surfaces 3! which converge to a sharp forward edge 32. The shock wave W forms at this edge 32 and its angle is a direct function of the Mach number of night, as will be more fully described. The wedge element 25 is carried by an arm 33 projecting forwardly from a. mounting cradle 36. The cradle 34 is arranged within the wing H and the arm 33 projects forwardly through an elongated slot 35 in the wing skin to support the wedge element in front of the wing. For reasons which will later a ms-ab become apparent, the mere- 34 i's'fmourited to tilt or pivo't ab'oilta horiiontal 'aitis. In'th'e arrangement illustrated, bolts or pins 36 engage ino'penin'gs in lugs 31 on the 'c'radl'e '34 and the wing structure to "support "the cradl'e for pivotal movement. 7

The cradle 34 has an upstanding flange -38 spaced'ahead of its pivotal axis and the arm 33, which carries fthefw'edg'e element, projects forwardly from the flange. it is to be understood that the mounting c'ra'dle '3'4 isprefer'ably housed within the wing H or other part of the aircraft structure, while the wedgeeiement 25 is carried by the arms3 so asto be in the 'freeair stream in front of the wing br other p'aft of the craft.

The means '26 for sensing the angle of "the shock wave W --generated at "the wedge element 2 5, is an important part of the invention and operates on the principle that the angle which the shock'wave makes with the free air stream is'a'functiono'f the half angle of the wedge ele- 'ment 25 and the'rela-tive velocity of the free air stream or Mach number. By'sensing or determining this angle of theshock wave Wthe means constitutes anaccurate instrumentality from which the Mach number-of the craft may be ascertained, the half angle of the wedge element being known and the Mach number being the variable factor. The means 26 includes a pressure receiving tube 40 which I will term'a'total head tube supported for fo'reand aft movement. The tube '48 is located atone side of the wedge ele- 'ment, being shown spaced above the element in the drawings, and is arranged so that it may-fol flow the shock waveas'i ts angle changes during flight. The forward end of-the tube 48 isopen to receive the head pressure at or adjacent the shock wave and the-rear end of the tube is carried by a translatable member which may be in the form of an internally threadedsleeve or mil; "4!. 'The nut 4|, in turn, is slida'bly andnon-ro- "tatably guided in the opening 42 of a guide 43. The guide tis supported-in an opening 44 in the flange 38 so that the "nut '4l extends forwardly beyond the flange, as s'hown in Figure 2. The total headtube and its suppo'rtingnut 4| extend through a'sl'ot 45 in theskin of th wing l'i so that "the "tube extends into the air stream in advance of the-wing. 'A fieiiible'line 'or'tube 45 com- Inunicat's with the'rear end of the'tube 4B and 0 extends to a pressuresensitive unit, to be later described.

The :means -16, for sensing the angle of the shock waveformed at the wedge element 25, further-includes a second total head'tube 4! for re 'ceiving or sensing the indicatcdfree stream total pressure. The tube "41 has its open forward end projecting beyond the leading edge 32 of the wedge element 25, as best shown in Figure 3, to be in the free air stream. The tube 41 extends "through an opening 48 in the wedgeelement 25 "and arm 33 to pass rearwardly into the wing structure. The rear exposed portion of thetube 4 1 is preferably flexible.

When a tube, 'suchasth'e tube '41, is arranged with its forward end in a free supersonic'air 'strea'm, abow wave forms in front of the tube *and 'the pressure "received or sensed by the tube is considerably below the true value, there being a substantial loss in 'pressure byreason of the bow wave. Onthe other handwhen such a tube is located behind a shockwa've, such as generated by th'e we'd'g'e leme'nt 25, it isin a region ofa lower Mach number and there is l'ess loss as a r esult cordingly, the pressure sensed by a -tube behind use angular shock wave "W is greater than that registered by a tube located' inthe-free supersonic air stres'mandir the tube behind the slit) wave W is moved forwardly, it s'en-ses ro'gressive1y lower pressures until it passes into the free air stream where it recives'the -same pressure-as the other tube. In the present invention, the tube 41 is located in the free'supers'onic'air'stream to sense or receive a pressure considerably below the "true value while the tube may be shoved forwardly andrearwardly throughthe shock wave "W to s'ehse higher and lower pressures and thus sense or locate the position of the shocks/ave.

The-means 26-i urther includes apressure sensitive mechanism responsive to the pressures received by the tubes 40 and. This mechanism includes 'a sealed or closed pressure cell '48 partitioned by a transverse flexible diaphragm into two chambers '50 and 5|. The above described tube 46, leading from the movable total head tube '40, communicates with the chamber50 while the indicated total head tube 4-! communicates with thechambe'r 5|. Switches52 and-53 are adjustably supported in' the chambers 50 and5 l respectively to be controlled or actuated by'the diaphragm 49. Any appropriate'means may be employ'eti for adjustably supporting the switches '52 a'nd53 tobejin the correct relation to the diaphragm. I'n thecase illustrated in-F'igureS 'Z and 11, adjusting screws 54 are threaded through openings 55 in the wall -'of the cell 48 and have swivel or rotary connections 56 with bosses '51 on the switches. By-simply rotating the screws 54,=the switches 52 and5'3 may be separately adjusted toward or-awa'y from the diaphragm 49. The diaphragm 4'9 may carry buttons 58 for engaging andactuating thecontrol members of the switches.

The switches 52-"and-53 serve to control a reversible electric motor 59 'for moving the head tube "Mt'forw'ar'dly and rearwar'dly. As schematically illu'str'ated in Figure '10, the switches 52 and 53 are interposed inth'e forward and reverse energizing lines 60 and 6i leading'from a power line-62 to the motor 59. The screws 54 are manipulated prior to use of the equipment to adjust the positions of the switches 5'2and53 so that when the pressures in the chambers 50 and 5| "are equal, andthediaphragm is in an intermediate undisturbed position, the switch '52 is closed by'virtue of theengagement of the diaphragm button 58 with the control memberof "the switch. The shaft'of the motor' 59 has ascrew "threaded extension E3 which has engagement 'withaninte'rnaI thread on the nut or sleeve 4|. The circuit ofthe reversible motor 59 is such'that the shaft extension 63 is rotated in i the direction to move the headtubelfl rearwardly when the pressures in the chambers 50 and 5| are equal and the switch 52 is closed. The switches52 and 53 are preferably-of the type that'require only minor -move'm'erits of their actuation. For example, theymay'be'of theclassinarketed under the trade-name Micro-switch. During supersonic flight, rearward movement or the head --tube 4fl by'-virtue=of energization of the motor 59 may move'the tube 40 rearWardl'y through the 'shock Wave W. When'this occurs, the tube4ll "senses a higher-pres'sure which is transmitted't'o the V chamber 5n and this pressure deflects the diaphragm!!! away from the switch 52 opening the circuit throu'gh the-line and stopping the inotor'k'ill. "If the forward-endof the head tube f tl'ie bow Wavewhibh fofms infioiit-lifit. Ac- "15 0 movesbehind the'Shockwave W or if theshock wave moves ahead of the tube by reason'of a change in velocity of the craft, a higher pressure is sensed by the tube 40. This increased pressure is transmitted to the chamber 50 and deflects the diaphragm 49 to close the switch 53 energizing the motor 59. The motor 59, energized through the power line 6|, rotates the threaded extension 63 to advance the tube 40 into its equilibrium position in the shock wave W.

From the foregoing it will be seen that the forward end of the head tube 40 is automatically maintained in or adjacent the shock wave W during supersonic flight. It is this automatically maintained variable position of the tube 4!! that is indicative of the speed of flight and the position of the tube 40 and its associated parts is utilized to govern the instrumentalities which visibly indicate the velocity of flight, control the fuel system, etc.

However, in aircraft, guided missiles, and airplanes, where the attitude of flight is subject to alteration, the above described means 26 for sensing or following the angle of the shock wave W, requires an additive means 21 to compensate for the resultant change in the angle of attack. The above mentioned means 21 serves to automatically preserve a substantially constant or zero angle of attack for the wedge element 25 and thus eliminate errors that would otherwise result from changes in the angle of attack of the craft.

The means 21 includes a pair of static pressure taps or orifices 66 and 8! in the upper and lower surfaces respectively of the wedge element 25 for sensing the angle of attack of the element. Lines or tubes 68 and 59 extend rearwardly from the orifices and are flexible or, at least, their rear portions are flexible. A sealed or closed cell H1 is arranged in the aircraft structure and its interior is divided into two chambers H and 12 by a transverse flexible diaphragm 13. The line 68 from the upper orifice 65, has communication with the chamber H and the line 19 from the lower orifice communicates with the chamber 13. 'A switch 14 is arranged at one side of the diaphragm l3 and a. similar switch 75 is positioned at the other side of the diaphragm. The switches l4 and 15 may be of the same type as the switches 52 and 53, described above, and are adjustably supported in the cell by means 18 which may be the same as the adjusting means 54555B51 shown in detail in Figure 11. The buttons TI on the flexible diaphragm l3 serve to actuate the switches 14 and 75 when the diaphragm is flexed from its intermediate undisturbed position. The static pressures at the opposite sides of the wedge element 25 are transmitted to the chambers H and 12 by the orifices 66 and 61 and their respective lines 68 and 59. When these static pressures change, owing to a change in the angle of attack of the wedge element 25, the pressures in the diaphragm chambers H and i2 become unbalanced and the diaphragm i6 is flexed to close the switch 14 or 15. The two sealed cells 48 and '10 may be mounted on a suitable common support 18, as shown in Figure 2.

The means 21 further includes a reversible electric motor [9 controlled by the switches 14 and and operable to pivot the wedge element 25 on its hinge pins 36 in response to the static pressures received at the orifices 6B and 61. The

motor 19 is carried by the pivoted cradle 34 of the wedge element 25 and its shaft carries a jack-screw 80. The screw 80 threadedly operates in a nut 8| which has a pivoted link connection 82- with the aircraft structure. The motor 19 and its j ack-screw 89 are spaced rearwardly from the pivotal axis of the cradle 34 and the axis of rotation of the screw is substantially perpendicular to the cradle so that upon rotation of the screw the cradle and the wedge element 25 are pivoted on their hinge pins 35. The switch '14 in the diaphragm chamber H, controls a forward energizing lead 83 of the motor 79 and the switch is connected in the reversing line 84 of the motor. When the angle of attack of the wedge element 25 changes slightly, the pressure at one side of the element, say the upper side, is greater than at the lower side so that the pressure in the chamber 1! becomes greater than the pressure in the chamber 12. This flexes the diaphragm 13 to close the switch 15 and the motor 19 is energized to pivot the wedge element 25 to a position where the angle of attack is substantially zero. With the angle of attack at zero, the pressures in the chambers ll and 12 equalize and the diaphragm 73 returns to a neutral position where both switches i l and 75 are open and the motor 19 is deenergized. It will be readily understood how the means 2*! just described operates to automatically maintain the wedge element 25 at the substantially zero angle of attack in response to changes or differentials in the static pressures received at the orifices 56 and 61.

The means .28 for visibly indicating the supersonic Mach number of flight of the craft, serves to receive or respond to the position of the total head tube 49 and to transmit this information to any selected place in the aircraft, converting the information thus transmitted into a visible indication of the Mach number. The means 28 includes a set or pair of synchronous units 84 and 35. The synchronous units may be of the general class known to the trade as Selsyn, Autosyn or Synchrotie devices, the unit 84 being in the nature of the generator or transmitter and the unit 85 being the synchromotor or receiver. Such synchronous transmitters and receivers are well known in the art and their details are not believed to be essential to an understanding of the present invention. It is believed that it will suffice to say that each unit 84 and 85 has three stator windings and a rotor winding, the corresponding stator terminals of the two units being connected by electrical connections 86 and the construction and arrangement being such that upon angular movement of the transmitter rotor a set of three single phase voltages is transmitted to the receiver 85 to cause the receiver rotor to turn to the same angular position as the transmitter rotor. When the rotors of the two units 84 and 85 are in the same angular position the stator voltages are opposed and zero current passes between the units but upon angular movement of the transmitter rotor in either direction, an electrical signal comprising the three single phase voltages, is transmitted by the unit 84 through the lines 86 to the stator windings of the unit 85 and the rotor of the unit 85 immediately assumes the same position as the rotor of the transmitter. Power lines 81 and 88 carry energizing current to the rotor windings of the synchronous units 84 and 85.

The synchronous generator or transmitter unit 84 is associated with the total head tube 40 so that a change in the position of the tube is immediately reflected in a corresponding change in the position of the rotor of the transmitter. In the preferred arrangement illustrated, the transmitter unit 8-1 is coupled with the shaft of the. motor 59 through a suitable speed reduction gearunit 9I so that the motor which moves the tube 49 in response to the pressure sensed or received by the tube 49, also moves the rotor of the unit 84 in the same angular direction and in a proportionate manner. The means 29 further includes a dial 98 positioned to be visible to the pilot or engineer and-calibrated in terms of Mach number. A hand 9911s. movable across the dial in cooperation with its calibrations and the shaft 99- ofthe hand 89 is connected with the rotor of the receiver unit 8,5,so that the position of the hand reflects the angular position of the rotors of the two units 84 and 95 and therefore indicates the Mach number of the aircraft as sensed or determined by the movable head tube 49. The meter dial 883. is calibrated according to the angle sensing. movements of the tube 49 so that the hand 89 cooperating therewith indicates the true Machnumber of flight.

The means. 29, which is responsive to or controlled by the means 25 for sensing the angle of the shock wave. W, regulates the delivery of fuel to the powerplant P. The means 29 includes a suitable regulating valve 92 interposed in the iuel supply pipe I! of the powerplant. The valve 92; is actuated by a reversible electric motor 93. A speed reducing gear box 94 is associated with the. shalt of the motor 93 and drives a screw shaft 95. The screw shaft 95 in turn operates a nut, 99,. which is operatively connected with the lever 91 of the valve 92 by a link 99. The forward and reverse energizing leads 99' and I99 of the reversible electric motor; 93 extend to two independent. halves IN and I92 of a rheostat, see Figured. The rheostat windings MI and I92 are supported onadisc I99. mounted to rotate or turn with respectto a stationarily supported dial I94. A central. shaft I95 supports the disc I93 on the dial for, rotation, the rotary mounting being such that the. rheostat disc remains stationary until deliberately manually moved. The face of the dial. 599, is calibrated in Mach numbers and the rheostat disc !93 has a pointer finger I99 which cooperates with the calibrations. The finger I99 may also form a handle for manually turning the rheostat disc.

The fuel regulating means further includes a synchronous receiver or motor I91 which may be similar to, the receiver unit 55 referred to above. Power leads I99 extend to the rotor winding of the receiver unit 19? and electrical conductors i99 are tapped off. the above described connections iii and, extend to. the stator winding terminals. of the unit L9]. The synchronous receiver unit, I91 serves to drive or turn a rotor H9 which moves across the rheostat windings ill! and I92. Apower lead MI is connected with the brush or rotor M9 to supply energizing current to the. motor 93 when the rotor H9 is in engagement with either one of the rheostat windings Iii-I or i192. The rheostat windings I9! and IE2 are spaced apart to leave a dead zone or null point and whentherotor I i9. is at this null point the reversible motor 93 is deenergized so that the valve 92 is stationary. However, when a signal is received by the synchronous unit I9! from the. transmitter 84, the rotor H9 is moved from the null; point to cooperate with one orthe other of the rheostat windings I9I or I92 to 91131? gize the motor 93 and operate the valve 92 By manually setting or adjusting the finger I99 at a selected Mach number calibration on the dial H141, he ean 2- .Q m n hr h the me ium 19 of; the synchronousunits 8 4; and I9], will auto-. matically regulate the valve 92 to supply fuel to the powerplant P in sufficient quantity to maintain the Mach number thus selected.

When the craft is, flying at the selected Machnumber, the rheostat brush or rotor II9 is at, the null point between the two rheostat windings 19-5, and H32. If thevelocity of the craft decreases, the means 2S causes the tube 49 to follow the change in the angle of the shock wave W by energizing the motor 59 as previously described. This operation of the motor 59 changes the angular position of the rotor of the synchronous transmitting unit 84 and a signal is transmitted to the receiver unit I91. The rotor of the receiver unit I91 changes position accordingly and the brush or rotor H9 is. moved from the null position into contact with the rheostat winding I92. Current then flows through the wire HI, brush II9, winding I92 and line 99 to the motor 93 energizing the. motor so that it rotates the screw 95- in the direction to increase the fuel flow through the valve 92-, the speed of the motor being dependent upon the position assumed by the brush II9 on; the winding I92. The additional flowof fuel to the powerplant P increases the speed or Mach number of' the craft and the tube 49 by sensing the. change inthe angle of the. shock; wave W, is moved by the motor 59 to follow the shock wave. This energization of the motor 59 is, accompanied by actuation of the transmitting unit 84 and a signal is sent to the receiver unit I91 to move the brush I I9 to the null point between the rheostat windings IM and I92 stoppingthe motor 94 so that the throttle valve 92 is held at the new setting. Conversely an increase in the Mach number of flight of the craft causes the means 25 to transmit a signal to the receiver unit I91 Whichin turnmoves the brush or rotor- I I9 into cooperation with the rheostat winding I-9 I and the, motor 93 is energized is throttle down the valve 92. As a result, the Mach number of the craft decreases and the angle of the shock wave W changes so that a signal is transmitted to the receiver unit I9] to bring the rotor or brush H9 to the null point. From this it will be seen that the means 29; as controlled by the means 26, automatically regulates the supply of fuel to the powerplant P in accordance with the manual setting of the finger 16- to maintain a selected Mach number of flight.

The means 39, which is controlled by the shock wave sensing means 26, serves to alter the extent of projection of the brake part 29 in accordance with the Mach number of the craft. The-means 39 includes a reversible electric motor I29 which drives a lead screw I,- 2I through the medium of a suitable speed reduction gearing I22. The screw I ll in turn operates a nut I24. which is operatively connected with the pivoted brake B through linkage I25. The forward and reverse connections I29 and I21 of the motor 29 extend to rheostat windings I28 and I29. The rheostat windings I28 and I29 are carried by a manually @dl'ustable. disc I39 and are adapted to be engaged by a movable brush or rotor I31. The rheostat windings I28 and I29, the disc I39 and the brush I'3 I may be of the same construction as the windings IM and I92, the disc I93, and the brush or rotor H9 respectively, described above, and the disc I93 has a manual adjusting fin er I3 op ra g r a al H3 in the sam manner-as the finger I96. A lead I35 connects the rotor or brush I3Iz with the power line so that the motor I20 is energized when the brush isin cooperation with either winding I28 or I29. The means 35 further includes a synchronous motor or receiver I35 for operating the rheostat rotor ISI. Leads I 36 are tapped into the above described conductors 85 and extend to the stator winding terminals of the receiver unit I34 to carry the synchronous transmitter signals to the receiver and power lines 9 supply the current to receiver rotor.

Where the apparatus includes the fuel supply regulating means 29 as well as the brake regulating means 39, it is desirable to provide a selector switch arrangement so that either one of the means 29 or 30 may be conditioned for operation while the other means 29 or 30 is made idle. Any selected switch system or device may be employed for this purpose. In Figure 10, I have diagrammatically illustrated a single switch S which controls the two sets of electrical conductors I39 and I 36 leading to the synchronous receiver units Iil'i and I26 respectively. This switch includes pairs of spaced contacts Mil connected in the conductors 599 and a similar set of contacts I4I con nested in the lines I36. A rotor or shaft hi2 has three spaced blades I43 and is manually turnable between the position where the blades Hi3 cooperate with the contacts M to complete the circuit to the receiver unit IIT'I and the position where the blades I43 cooperate with the contacts I 4! to complete the circuit to the receiver unit I281. The full lines in Figure show the blades M3 in cooperation with the contacts [til of the lines "39 while the broken lines illustrate the blades in engagement with the contacts IM of the conductors I36. The switch S may also have an open position where its blades I43 are out of engagement with both sets of contacts I 40 and Ml.

The operation of the means 30 is substantially the same as the operation of the means 29 except, of course, that the brake B is moved in response to changes in the Mach number of the craft instead of the valve 92. Assuming that the switch S is in the position where the blades are in engagement with the contacts Ml, changes in the axial position of the total head tube 40, effected as above described, are accompanied by signals produced by the synchronous transmitter unit 84 and received by the receiver units 85 and I34. The receiver unit I34 in turn moves the rheostat brush or rotor I3! to cause either forward or reverse actuation of the motor I and retraction or projection of the brake part Zil. By adjusting the finger I32 to a selected setting, the means operates to obtain the desired action of the brake B.

It is believed that the operation of the apparatus will be readily understood from the foregoing detailed description which includes a description of operation of the several instrumentalities. The means '26, which senses the angle of the supersonic shock wave W, operates through the synchronous transmitter unit 84 to produce signals. These signals are received by the synchronous unit 85 which operates the hand 89 to visibly indicate to the pilot the speed of flightand may also be received either by the receiverunit I01 or the of the invention, I do not wish to be limited to the specific details set forth but reserve to myself any features or modifications that may fall within the scope of the following claims.

I claim as my invention:

1. A device for indicating the Mach number of a supersonic aircraft comprising an element carried by the craft and exposed to the free supersonic air stream, said element creating a shock wave during supersonic flight, the angle of the wave varying with changes in the Mach number of flight, means sensing the variations in the angle of said wave, and an indicating device responsive to said means for indicating the Mach number of flight.

2. A device for indicating the Mach number of flight of a supersonic craft comprising a generally wedge shaped element supported by the craft to have its convergent edge in the free supersonic air stream to create a shock wave, the angle of said Wave varying with changes in the Mach number of flight, means sensing the variations in the angle of said wave, and an indicating device responsive to said means for indicating the flight Mach number of the craft.

3. A device for indicating the Mach number of flight of a supersonic craft comprising a generally Wedge shaped element, means supporting the element on the craft for pivotal movement in a location where its convergent edge is in the free supersonic air stream to create a shock wave, the angle of the shock wave varying upon change in the Mach number of flight, means responsive to changes in the angle of attack of the element for automatically pivoting the element to maintain the element at a substantially zero angle of attack, means for sensing the angle of said shock wave, and means responsive to said sensing means for indicating the flight Mach number of the craft.

4. A Mach meter for a supersonic aircraft comprising an element having surfaces converging to an edge, means for supporting the element on the craft in a position where said edge faces forwardly in the free air stream to create a shock wave, the angle of said shock wave with respect to the air stream varying with the Mach number of flight, means for sensing the angle of said wave including a head tube, means supporting the tube for movement, and means responsive to the pressure received by the tube for moving the tube to maintain its pressure receiving end in or adjacent the shock wave, and a device responsive to the changes in position of the tube for indicating the flight Mach number of the craft.

5. A Mach meter for a supersonic aircraft comprising an element having surfaces converging to an edge, means for movably supporting the element on the craft to have said edge face forwardly in the free air stream where it creates a shock wave, the angle of said wave with respect to the air stream varying with changes in the Mach number of flight, means for moving said element to maintain the same at a substantially zero angle of attack, a head tube supported for axial movement to have its pressure receiving end in or adjacent the shock wave, means responsive to the pressure received by said tube for moving the tube to maintain its said end in or adjacent the wave, and means actuated in accordance with the position of said tube for indicating the flight Mach number of the craft.

6. A Mach meter for supersonic aircraft comprising an element having surfaces converging to an edge, means for movably supporting the element on the craft to have said edge face foraura-mo wardly in thefree air stream where it creates a shock wave, the angle of said'wave with respect to-the air stream varying with changes in the Mach number of flight, means responsive to the static pressures at the opposite sides of said edge for moving said element to maintain the same at a substantially zero angle of attack, a head tube supported for axial movement to have its pressure receiving end in or adjacent the shock wave, means responsive to the pressure received by said tube for moving the tube to maintain-its said end in or adjacent the Wave, and means actuated in accordance With the position-of said tube for indicating the flight Mach number of the craft.

7. A device for indicating the flight Mach number of an aircraft comprising an element carried by the craft to be in the free airstream where it creates a shock Wave, a movable pressure receiving means for sensing the position of the shock Wave, means responsive to the pressure sensed by said pressure sensing means for moving said sensing means to maintain the same at or adjacent the shock wave, and means actuated in accordance with the position of said sensing means for indicating the Mach number of the craft.

8; A device for indicating the flight Mach number of an aircraft comprising an element carried by the craft to be in the free airstream Where it creates a shock wave,a movable pressure receiving tube supported to receive the pressure at the shock Wave, means responsive to the pressure sensed by said tube for moving the tube to maintain the same at or adjacent the she wave, and means responsive tothe pressure thus received for indicating the flight Mach number of the craft.

9. A device for indicating the flight Mach number of an aircraft comprising an element on the craft in the freeair stream for generating a shock wave, means sensing the free air stream indicated total pressure, a movable means for sensing the total pressure at the shock Wave, means responsive to the pressures thus sensed for maintaining said movable means at or adjacent the shock Wave, and means responsive to the pressures thus sensed for indicating the Mach number of the craft.

10. A device for indicating the flight Mach number of an aircraft comprising an element on the craft in the free air stream for generating a shock Wave, means sensing the free air stream indicated total pressure, a movable means for sensing the total pressure at the shock wave, responsive to the pressures thus sensed for maineining said movable means at or adjacent the shock Wave, and means responsive to the pressures thus SGDSEdi for indicating the Mach number of the craft, including a remote indicator, a signal transmitter actuated by the means for maintaining the movable means at the shock Waveand a receiver actuated by the signals from the transmitter for operating the indicator.

111. A device for indicating the flight Mach number of a supersonic crait'comprising an element movablymounted on the craft to be in the free air stream where it creates a shock Wave, a tube in the free air stream for sensing the indicated air stream total pressure, a movable tube arranged to sense the total pressure at the shock Wave, motor means for moving the movable tube, pressure sensitive means responsive to the pressures sensed by said tubes for controlling the motor means so that the latter maintains the movable tube at or adjacent the shock Wave, a Mach number indicating meter, means responsive to the action of the motor means and therefore to the position of the movable tube for operating the meter, and means for moving said element to maintain it at the zero angle of attack.

12. A device for indicating the flight Mach number of' a supersonic craft comprising an element movably mounted on the craft to be in the free air stream Where it creates a shock Wave, a tube in the free air stream for sensing the indicated air stream total pressure, a movable tube arranged to sense the total pressure at the shock wave, motor means for moving the movable tube, pressure sensitive means responsive to the pressures sensed by-said tubes for controlling the motor means so that the latter maintains the movable tube at or adjacent the shock wave, a Mach num-, ber indicating meter, means responsive to the action of the motor means and therefore to the position of the movable tube for operating the meter, and means for moving said element to maintain it at or adjacent the zero angle of attack including motor means for moving the element, means for sensing the static pressures at the opposite sides of the element, and pressure sensitive means responsive to said static pressures for controlling the last named motor means.

13. A device for indicating the flight Mach number of a supersonic craft comprising an element movably mounted on the craft to be in the free air stream where it creates a shock wave, a tube in the free air stream for sensing the indicated airstream total pressure, a movable tube arranged to sense the total pressure at the shock Wave, motor means for moving the movable tube, pressure sensitive means responsive to the pressures sensed by said tubes for controlling the motor means so that the latter maintains the movable tube in :position to sense the shock wave during changes in the Mach number of flight which change the angle of the wave, a remote Mach number indicatine meter, a synchronous transmitter responsive to the position of the motor means and therefore to the position of the movable tube, a synchronous receiver for controlling the meter actuated by signals from the transmitter, and means for moving said element to maintain it at or adjacent the zero angle of attack.

14. In a supersonic aircraft having a powerplant, avalve for controlling the delivery of fuel to the powerplant, an element carried by the craft to'be in the free air stream (Where it creates a shock wave, a movable tube arranged to sense the total pressure at the shock wave, motor means for moving the tube, pressure sensitive means responsive to the pressure sensed by the tube for controlling the motor means to maintain the tube in position to sense the shock wave during changes in the flight Mach number of the craft, and means responsive to the position of the motor means and therefore to the position of the tube for operating said valve.

15. In a, supersonic aircraft having a propulsive powerplant, a control for the povverplant for regulating its propulsive action, an element carried by thev craft to be in the free air stream Where it creates a. shock Wave, a movable pressure sensing member arranged to sense the total pressure at the shock wave, pressure sensitive means responsive to the pressure sensed by the member for moving the member to maintain it in position to sense the pressure at the shock wave during changes in the flight Mach number of the craft, and means operated in accordance with the position of said member for regulating said control to obtain a given propulsive action of the powerplant.

16. In a supersonic aircraft having a propulsive powerplant, a control for the powerplant for regulating its propulsive action, an element movably carried by the craft to be in, the free air stream where it creates a shock wave, a movable pressure sensing member arranged to sense the total pressure at the shock Wave, pressure sensitive means responsive to the pressure sensed by the member for moving the member to maintain it in position to sense the pressure at the shock Wave during changes in the flight Mach number of the craft, means for moving said element to retain it at a substantially zero angle of attack, and means operated in accordance with the position of said member for regulating said control to obtain a given propulsive action for the powerplant.

17-. In a supersonic aircraft, having a powerplant, a valve for controlling the delivery of fuel to the powerplant, an element carried by the craft to be in the free air stream where it creates a shock wave, a movable tube arranged to sense the total pressure at the shock wave, motor means for moving the tube, pressure sensitive means responsive to the pressure sensed by the tube ior'controlling the motor means to maintain the tube in position to sense the shock wave during changes in the flight Mach number of the craft, a synchronous transmitter unit controlled by the motor means, a synchronous receiver unit controlled by signals from the transmitter unit, and means for operating the valve controlled by the receiver unit to operate the valve in accordance with the position of the motor means and said tube.

18. In a supersonic aircraft having a powerplant, a valve for controlling the delivery of fuel to the powerplant, an element carried by the craft to be in the free air stream where it creates a shock Wave, a movable tube arranged tosense the total pressure at the shock wave, motor means for moving the tube, pressure sensitive means responsive to the pressure sensed by the tube for controlling the motor means to maintain the tube in position to sense the shock wave during changes in the flight Mach number of the craft, motor means for operating said valve, means operating in accordance wvith the position of the first named motor means and therefore with the position of the tube for controlling the second named motor means, and means for manually setting the last mentioned means to obtain a selected speed of flight of the craft.

19. In a supersonic aircraft having a propulsive powerplant, a control for the powerplant for regulating its propulsive action, an element carried by the craft to be in the free air stream where it creates a shock wave, a movable pressure sensing member arranged to sense the total pressure at the shock wave, pressure sensitive means responsive to the pressure sensed by the member for moving the member to maintain it in position to sense the pressure at the shock wave during changes in the flight Mach number of the craft,

16 a Mach number indicator, and means operated in accordance with the position of said member for regulating said control to obtain a given propulsive action of the powerplant and for operating said indicator.

20. In a supersonic aircraft having a propulsive powerplant, a control for the powerplant for regulating its propulsive action, an element carried by the craft to be in the free air stream where it creates a shock wave, a movable pressure sensing member arranged to sense the total pressure at the shock wave, pressure sensitive means responsive to the pressure sensed by the member for moving the member to maintain it in position to sense the pressure at the shock Wave during changes in the flight Mach number of the craft, a Mach number indicator, and means operated in accordance with the position of said member for regulating said control to obtain a given propulsive action of the powerplant and for operating said indicator including a, synchronous transmitter unit operated by the pressure sensitive means, and a pair of synchronous receiver units coupled with the transmitter unit to operate in I synchronism therewith, one of the receiver units controlling said indicator, the other operating said control.

21. In a supersonic aircraft, a brake part projectable variable distances from the craft, an element carried by the craft to be in the free air stream where it creates a shock wave, means for sensing the position of the shock wave during changes in the flight Mach number of the craft including a movable member for sensing the total pressure at the wave, means responsive to the pressure thus sensed by said member for projecting and retracting the brake part in accordance with the Mach number of flight, and means for manually pie-selecting the action of the last named means.

22. In a supersonic aircraft, a brake part projectable variable distances from the craft, an element carried by the craft to be in the free air stream where it creates a shock wave, means for sensing the position of the shock wave including a movable tube arranged to sense the pressure at the wave, motor means for moving the tube, means sensitive to the pressure sensed by the tube for controlling the motor means to maintain the tube at the shock wave, and means for operating the brake part in accordance with the position of said tube.

FRANK A. CLEVELAND, II.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,978,863 Gregg et a1 Oct. 30, 1934 2,029,700 Boykow Feb. 4, 1936 2,179,500 Diehl Nov. 14, 1939 2,237,306 Hood Apr. 8, 1941 2,279,615 Bugatti Apr. 14, 1942 2,343,281 Crane Mar. 7, 1944 2,392,443 Youngman Jan. 8, 1946 

